Lying

The Noble Messenger of Allah (Allah bless him and give him peace) was asked: "Can a believer be a coward?" The Prophet said: "Yes." He was then asked: "Can a believer be a miser?" He replied: "Yes." And finally, he was asked: 'Can a believer be a liar?" The Prophet said: "No." (Al-Muwatta, Volume 56, Hadith 19)

He (Allah bless him and give him peace) said, “Maintain truthfulness, for truthfulness leads to righteousness, and righteousness leads to Heaven. A man continues to maintain truthfulness until he is recorded in Allah’s book as truthful. Refrain from lying, because lying leads to blatant evil, and evil leads to the fire. A man continues to lie until he is recorded in Allah’s book as a liar" (Related by Al-Bukhari, Muslim, Abu Dawood and Al-Tirmithi).

The Messenger of Allah (Allah bless him and give him peace) also said, "Honesty descended from the Heavens and settled in the roots of the hearts of men (faithful believers), and then the Quran was revealed and the people read the Quran, (and learnt it from it) and also learnt it from the Sunna." (See Hadith No. 208)

and “Lying is not good, whether in seriousness or joking.” (Related by al-Bayhaqiyy.)

and, he also said, “Do not ever lie, because lying leads to very abhorrent sins, and those in turn lead to Hellfire. One keeps on lying and seeks to do that until one is recorded as a liar in some books of Allah.” (Narrated by Ibn Majah.)